My Dell XPS 13 have a terrible connection and I have a limited range of where it will connect to my router(15-20ft). I have tried to turn off the power manager but it doesn't seem to make too much of a difference.

sudo modprobe iwlwifi 11n_disable=1

I also tried to disable hardware. I didn't notice too much of a difference. But I could have also done it incorrectly. (how do I know if I did this right/wrong?)

This is a known problem with the device itself, it also happens on Windows. In the following monster thread with more than 70 pages, you can see that over a period of two years Intel is continuously failing to fix this device. And it looks like they will never be able to get it working.

The only solution is to toss this piece of crap card out of the window and buy another model.

Somewhat ironically, that vendor forum is currently down for maintenance. In the mean time, an archived copy of the "monster thread" referred to in this post may be accessed here.
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Eliah KaganAug 14 '14 at 15:28